This project is designed to study the possible intrarenal action of angiotensin II on renal blood flow and tubular sodium handling. Using an inhibitor of angiotensin I converting enzyme, changes in renal function including intrarenal distribution of blood flow will be measured. Renal blood flow will be measured using an electromagnetic flowmeter and glomerular filtration rate estimated by clearance of inulin. Intrarenal distribution of renal blood flow will be measured by the microsphere method. Sodium, potassium and phosphate excretion will be followed. By administering this inhibitory drug under a variety of conditions, we hope to further clarify the nature of the action of the renin-angiotensin system. All experiments will be carried out in anesthetized dogs.